Cobalt Phthalocyanine-Based\nCovalent Organic Framework\nwith Bimetallic Synergistic Effect for Efficient Photocatalytic CO<sub>2</sub> Reduction

Covalent organic frameworks (COFs) have emerged as promising\nphotocatalysts\nfor the CO<sub>2</sub> reduction reaction (CO<sub>2</sub>RR). Among\nvarious building components, metal phthalocyanines have gained significant\nattention owing to their excellent photochemical properties and well-defined\nM–N<sub>4</sub> sites. Herein, tetraanhydrides of 2,3,9,10,16,17,23,24-octacarboxyphthalocyanine\ncobalt(II) (CoTAPc) are used as connection points to couple with bipyridine\n(bpy) for constructing an imine linked CoPc-bpy COF and then coordinated\nwith Re(CO)<sub>3</sub>Cl to create a novel CoPc-Rebpy COF. It is\nfound that there exists an intramolecular charge transfer from the\nCoPc to Rebpy units and then to Re center for CO<sub>2</sub>RR via\nZ-scheme molecular heterojunction mechanism. Under visible light illumination,\nthe CoPc-bpy and CoPc-Rebpy COFs deliver CO yields of 3068 and 6680\nμmol g<sup>–1</sup> h<sup>–1</sup>, respectively.\nThe significantly increased activity of CoPc-Rebpy COF can be ascribed\nto the synergistic effect of Re catalytic sites and the electron capture\ncenter provided by the CoPc unit. These findings present an effective\nstrategy for COF-based photocatalysts for CO<sub>2</sub>RR.